I have been an avid user of the GH series since the GH1. I use these cameras mostly for video, because I shoot Canon DSLRs for most of my stills. The GH series cameras are optimized for video and produce crisper video than the Canon DSLRs, whereas the Canon DSLRs have more dynamic range and color depth and less noise at all ISOs. I have been following the GH13 firmware patches by Russian hacker Vitaly on Personal View since the beginning and have applied the hacks to the GH1 and GH2 with mixed results.The GH3 now has a more solid weatherproofed build and the buttons are laid out like a true DSLR. It's like the GH2 has grown up to compete head to head in the DSLR market. But can it really compete with the big boys? You can read about the improved build and other new features in many reviews, but I'm going to focus here mostly on image quality.While the GH2 was an improvement over the GH1, the advertized gains in low light (noise) and dynamic range performance were a disappointment*. Still photography images were virtually the same, but the quality of motion video was improved considerably, particularly if the hack was applied.My first test of the GH3 was taking still photographs in controlled studio lighting. First impression of the JPEGs out of the camera is very good. Although at low ISO the difference from the GH2 is hard to see at first, upon examination there is significantly more detail in the shadow areas, the reds are richer, and the overall tint is more accurate. The GH2 images appear to have a green cast by comparison.Moving up into the higher ISOs, around ISO 3200 the differences are stark. Here the GH2 has blotchy noise, a muddy green cast in the shadows and the colors are muted. The GH3 retains finer grain all the way up to ISO 6400, the colors are bright and the images are actually usable. At 100% the GH3 has some mosquito JPEG artifacts evident as random pinpoints of noise vs. the GH2 which has dark blotches and smeared details.After upgrading ACR to handle the new RAW files, I took another look at the same set of photos in RAW. The RAW files reveal the fact that the JPEG engine in the GH3 is doing a heavy amount of noise reduction. Even at the base ISO of 200, quite a bit of noise is present in the RAW images, more than I would like to see. With an aggressive amount of noise reduction applied, the RAW files can be made to look as good and then a bit better than the JPEGs out of the camera. But the conclusion is that the JPEG engine has already been optimized to make the images look as good as possible, and RAW processing is not gaining a whole lot, except for the ability to fine tune and fix any white balance errors.The still photos are pretty significantly improved over the GH2, and those already heavily invested in Micro 4/3 lenses will be glad to know that the investment will be put to good use on this body. But what many are dying to know is how much improvement there is in the video. What videographers are looking for is more dynamic range and a reduction or elimination of macroblocking and pixelation in heavy motion scenes.There is good news here too: The GH3 pulls moderately more detail out of the shadow areas than the GH2. It's subtle but it's there: there is a bit more detail and less pixelated busyness in the grain. Again at high ISOs the difference is more drastic. The new All-I MOV codec is much more solid and easier to grade and edit without the image falling apart, without resorting to hacking the firmware. The other significant change is that the new menu allows for setting sharpness, contrast, and noise reduction in five steps up or down rather than three. Even with the sharpness turned to -3 on the GH2, the video looked unnaturally sharp with halos and aliasing. Now, with the sharpness turned all the way down to -5, the video looks more natural and the halos and aliasing are gone. Sharpening can now be adjusted in post more tastefully. Unfortunately, Panasonic removed two of my favorite photo styles for shooting video: Smooth and Cinema. In fact, they renamed all of them except for Standard and now there are only five instead of seven. The new styles Natural and Portrait are good choices for video. There are also many scene and creative control styles that have major effects on the overall look.I have one main issue with this camera and that is the fact that the base ISO is 200. I didn't like it when they changed the base ISO from 100 to 160 on the GH2, and a base ISO of 200 is even worse. A base ISO of 200 on a micro 4/3 camera has about the same signal to noise ratio as ISO 800 on a full-frame DSLR**. That is hardly a very clean ''best'' setting. Smaller sensor cameras should be allowing us to begin at a LOWER base ISO, not a higher one, in order to have the finest grain and least amount of noise possible. And especially for video you really need to be able to shoot at lower ISOs in bright light, otherwise you are forced to have to use neutral density filters. The camera has an extended ISO that allows you to shoot at 125, but in manual movie mode it forces you back to ISO 200. Ideally I would like to be able to shoot at ISO 50 but at least all other digital cameras allow you to shoot at ISO 100. This is very frustrating and I don't understand why Panasonic doesn't allow this.My second problem with this camera is the cost. This Micro 4/3 camera now costs TWICE as much as a good consumer grade DSLR such as the Canon T41. Even after adding on a few standard lenses, the DSLR becomes a less expensive solution while producing superior still images.The loss of the multi-format sensor is a mixed bag. On the one hand, the 3x2 and 16x9 photos have lower resolution, and for video all your lenses are going to be slightly cropped compared to the GH2. On the other hand, this could be a positive if you are using legacy lenses such as B4 mount 2/3" lenses which have soft corners; some of the offending corners are cropped off. In the end, the improved image quality of this sensor wins out over the loss of the multi-format oversized sensor.The new WiFi feature is the most sophisticated of any camera. It allows you to remotely control the camera's functions from your smartphone, immediately play back pictures on your phone or TV, immediately send pictures to your PC as you take them, and send stored pictures to your smartphone/pc/cloud service/web service/printer. I have not yet tested the WiFi features.Here are the pros and cons of the GH3:Pros:Excellent JPEG EngineIncreased dynamic rangeImproved low light/high ISO performanceMore accurate colorsWider control over contrast, sharpness, saturation, & noise reductionVideo quality exceeds most DSLRsSturdy buildBetter button layoutBetter, larger LCDLonger lasting batteryRobust video codec that does not require a hack for pro editingFast and very accurate auto-focusIn-camera HDR works wellSilent electronic shutter optionSophisticated WiFi featuresCons:Base ISO of 200 is restrictive & frustratingRAW files reveal that true levels of noise are high even at base ISOVery little gains to be had shooting in RAWNo Smooth or Cinema picture stylesConsiderably more expensive than many DSLRsStill photography still inferior to most DSLRsLoss of multi-format sensor could be a complaint for some.My overall impression of the camera is very good, and I will probably be getting rid of the GH2 and finally giving up on the frustrating exercise of trying to get the 'perfect' hack settings out of it. The GH3 doesn't need the hack, with the robust 72 mbps MOV codec it's reliable and ready out of the box for professional cinematographers and hobbyists. The only thing that bothers me about it is not being able to shoot below ISO 200 in manual movie mode, but I will have to learn to live with that. The cost remains a big issue; for the same amount you could buy two GH2s and have some money left over to put towards the 12-35mm f/2.8 lens. GH2 hackers who already like what they have will probably want to wait until the cost comes down, and most photographers who don't shoot video will get more quality for their dollars with a DSLR.*DxOMark actually gave the GH2 sensor a lower rating than the GH1 in all three categories: Color Depth, Dynamic Range, and Low Light ISO.**I compared the RAW files. At ISO 200, the grain or noise from the GH3 is actually slightly WORSE than the Canon 5D Mark III at ISO 800.